Resistance (re) Flashcards

1
Q

What is potential difference equivalent to? (also what’s its units?)

A

Voltage (JC^-1)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define electro motive force

A

The energy converted to electrical energy per unit of charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define potential difference

A

A measure of energy, per unit of charge, transferred between two points in a circuit

[Energy converted from electrical potential energy to some other form per coulomb of change flowing from 1 point to the other]

(this is a retarded ass answer)
i mean that class was always ^^ if u know what i mean

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What the equation that relates voltage to energy changes in a circuit per unit charge? (retarded ass question)

(actually not too icky yano)

A

J = V x c

Work done = voltage x charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Look at the beginning of the first pages of the booklet

(because i cba to like explain this visual tasking type shit)

am pretty sure this part was “partly” useless

A

Well, u better get a good mark for this one, although this isn’t ideal or efficient (possibly?), it is what it is, Have Fun!

i mean, it appears to be?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is Ohms law?

A

The current in a metal wire at a constant temp. is proportional to the p.d. across it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the equation for voltage?

A

V = IR
Voltage = Current x Resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Define resistance

A

Anything that opposes the flow of charge (aka current)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What’s resistance measured in?

[but there’s also a chance that there may be more for this…?]

lol i think that was useless

A

Ohms (that symbol that looks like a pimple)

[we shall see]

agreeable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Number 1 way of finding P?
(power)

A

Current x Voltage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Number 2 way of finding P?
(power)

A

Current^2 x Resistance
I^2 x R

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Number 3 way of finding P?

A

Voltage^2 divided by Resistance
V^2 / R

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does resistance work specifically in 3 steps?

A
  1. As free electrons move thru wire, they collide with atoms + with one another, which slows them down
  2. Some of the energy is transferred to the atoms, makes them vibrate = increases temp
  3. Ye that’s resistance?
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the equation for resistivity?

A

Resistivity = (Resistance x Cross sectional area) divided by length
p = (RA)/L

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

State what each of these symbols are:

p = ?
R = ?
A = ?
L = ?

A

p = resistivity
R = resistance
A = cross sectional area
L = length

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

If temp. is low in a metal wire, what dat mean for the resistance?
(3 steps)

A

At low temperatures:

  1. Electrons can drift past positive metal ions with ease
  2. Cuz few collisions to slow em down
  3. Resistance is low
17
Q

If temp. is high in a metal wire, what da mean for the resistance?

A

At high temperatures:

  1. Positive ions vibrate with greater amplitude
  2. Electron-in collisions more frequent
  3. Flow of electrons slowed down
    [current reduced]
    RESISTANCE IS HIGH
18
Q

What’s the jig with resistance and resistivity

A

They directly proportional
You know what that means?
If resistance increases, resistivity increases

19
Q

Define semi conductor?

A

Component that can partially conduct electricity ig
+
changes resistance based on temp

20
Q

Why resistivity decrease with increasing temp. in semi conductors?
(3 steps)

A
  1. More electrons break free of their atoms
  2. Increase in number of electrons available for conduction
  3. Resistivity decreases
21
Q

Define super conductor?

A

A material that has 0 electrical resistance at absolute zero temperature

22
Q

What name given to a temp, for a conductor that its resistance drops rapidly due to temp. change?

A

The Critical/transition

23
Q

What’s superconductivity?
(gl man)

A

When it has 0 electrical resistance when temp. is either at absolute zero (0 degrees kelvin or -273 degrees Celsius) to liquid nitro temps. (77k, -196 degrees Celsius)

24
Q

gagagaga

what?

A

googoogoogo

baby as hell

25
Q

3 examples of use of superconductors?

A
  1. Maglev train
  2. MRI scanner
  3. Particle accelerators
26
Q

Explain maglev train

(superconductor) 2 things

A

Makes train levitate off track1. To produce strong magnetic field2. no resistance = higher speeds

  1. To produce strong magnetic field
  2. no resistance = higher speeds
27
Q

Explain MRI scanner

(superconductor) 4 things

A
  1. good for non-invasive medical diagnosis
  2. Strong magnetic field aligns hydrogen atoms in body
  3. Radio waves absorbed = emitted by hydrogen atoms
  4. Image of body produced
28
Q

Explain particle accelerators

(superconductor) 2 things {that was separated} <– fuck is the use of that symbol

u tell me bro, what is that symbol?

A
  1. Magnetic field keeps the particles in a beam
  2. And steers them around the circular detector